Battery pack

ABSTRACT

In order to provide a battery pack that can let a user accurately know the state of charge of the battery pack, a battery pack  100  of the present invention includes: a plurality of chip-type LEDs  71  to  75;  a printed board  40  on which the plurality of chip-type LEDs  71  to  75  are placed; a second casing  20  where LED openings  21  to  25  are provided in such a way as to correspond to the plurality of chip-type LEDs  71  to  75;  and moisture-proof resin  60  that is provided in such a way as to cover the plurality of chip-type LEDs  71  to  75  on the board, wherein height of the moisture-proof resin  60  between the plurality of chip-type LEDs  71  to  75  from a board surface of the printed board  40  is lower than height of the moisture-proof resin  60  on the plurality of chip-type LEDs  71  to  75  from the board surface of the printed board  40.

TECHNICAL FIELD

The present invention relates to a battery pack equipped with anindicator that includes a plurality of LEDs.

BACKGROUND ART

In order to display a charge level of a built-in secondary battery in abattery pack, one that is equipped with an indicator including aplurality of LEDs has been known. For example, in an indicator that isequipped with five LEDs, all the five LEDs are turned on for afull-charge level. As the charge level decreases, the number of LEDsbeing turned on is gradually decreased, thereby letting a user know theremaining amount of battery capacity and encouraging the user toappropriately recharge the battery.

For example, what is disclosed in Patent Document 1 (JP2008-91234A) isan electronics device that includes a circuit board on which a pluralityof LEDs are placed side by side and a casing that includes a pluralityof light windows in such a way that beams of the LEDs fixed on thecircuit board are independently released out of the casing, withpartition walls provided on boundaries of the LEDs fixed on the circuitboard.

-   Patent Document 1: JP2008-91234A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, a battery pack that is used in an electric motorcycle or thelike may be used in rain, or may be left in rain after being laid on itsside. Therefore, it is important to give waterproof properties to thebattery pack.

In the battery pack, a printed board on which a circuit is mounted tomanage and control the secondary battery is provided. In order to givewaterproof properties, the printed board is coated withmoisture-resistant resin.

If a plurality of chip-type LEDs, which constitute an indicator forshowing the charge level, are mounted on the above-described printedboard, the LEDs are coated with the above-described moisture-resistantresin as well.

The configuration of a conventional battery pack in which the printedboard coated with the above moisture-resistant resin is provided will bedescribed.

FIG. 8 is a perspective view of the conventional battery pack. In acasing of the battery pack, a battery cell assembly (which is forexample made up of lithium-ion-battery unit cells that are connected inseries or parallel, or in both), and a printed board on which a circuitfor controlling and managing the battery cell assembly is mounted areplaced. On the casing of the battery pack, an indicator section isdisposed in order to let a user know the state of charge of the batterycell assembly.

FIG. 9 schematically shows the cross-sectional structure of theindicator section. On the printed board, five chip-type LEDs aremounted. The upper portions of the chip-type LEDs are covered withmoisture-resistant resin, which has been applied to give waterproofproperties. Openings are provided on the casing for each of thechip-type LEDs. This makes it possible to check, from outside thecasing, whether each of the chip-type LEDs is being turned on or off.

Usually, on the surface of a light emitting section of the chip-typeLED, anti-reflection agents or fine uneven treatment (anti-glaretreatment) have been applied. However, such functionality could be lostwhen the chip-type LED is covered with moisture-resistant resin. It wasfound that, if the LEDs are placed adjacent to each other, lightpropagates through the moisture-resistant resin, resulting in theleakage of light into the adjacent LEDs.

For example, what is shown in the example of FIGS. 8 and 9 is the casewhere only the first and second chip-type LEDs from the right are beingswitched on. However, in this case, as indicated by arrow inside themoisture-resistant resin, light leaks from the LED that is emitting thelight. As a result, a user might visually recognize that the thirdchip-type LED from the right is emitting light, even though the thirdchip-type LED is actually not emitting light.

As described above, when a plurality of LEDs coated withmoisture-resistant resin are used as the indicator section of thebattery pack, the moisture-resistant resin functions as a medium thatconveys the light emitted from the LEDs. Accordingly, a user might seethe LED that is not emitting light as one that is emitting light. Theproblem is that this configuration makes it difficult to let the userknow exactly the state of charge of the battery pack.

Incidentally, Patent Document 1 (JP2008-91234A) discloses the method ofpreventing the light from leaking by laying partition walls between LEDsor taking other steps. However, such a method leads to another problem,or an increase in costs.

Means for Solving the Problems

To solve the above problems, a battery pack of the present inventionincludes: a plurality of LEDs; a board on which the plurality of LEDsare placed; a casing where openings are provided in such a way as tocorrespond to the plurality of LEDs; and moisture-proof resin that isprovided in such a way as to cover the plurality of LEDs on the board,wherein height of the moisture-proof resin between the plurality of LEDsfrom a surface of the board is lower than height of the moisture-proofresin on the plurality of LEDs from the surface of the board.

Advantages of the Invention

In the battery pack of the present invention, the height of themoisture-proof resin between the plurality of LEDs from the boardsurface is set lower than the height of the moisture-proof resin on theplurality of LEDs from the board surface. According to the battery packof the present invention, even if the moisture-proof resin functions asa medium that conveys the light emitted from the LEDs, there is almostno leakage of light into the adjacent LEDs, and a LED that is notemitting light is therefore not mistaken as emitting light. As a result,it is possible to let a user accurately know the state of charge of thebattery pack.

Moreover, in the battery pack of the present invention, there is no needto put partition walls between the LEDs. Therefore, it is possible toreduce costs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a battery pack 100 accordingto the present embodiment.

FIG. 2 is a diagram for explaining a production process of a printedboard 40 of the battery pack 100 of the present embodiment.

FIG. 3 is a perspective view of the battery pack 100 of the presentembodiment.

FIG. 4 is a cross-sectional view of FIG. 3 taken along A-A′.

FIG. 5 is a diagram showing a cross section of a battery pack 100according to a comparative example.

FIG. 6 is a diagram showing a cross section of a battery pack 100according to a comparative example.

FIG. 7 is a diagram showing a cross section of a battery pack 100according to a comparative example.

FIG. 8 is a perspective view of a conventional battery pack.

FIG. 9 is a diagram showing the cross-sectional structure of anindicator section of the conventional battery pack.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be describedwith reference to the accompanying drawings. FIG. 1 is an explodedperspective view of a battery pack 100 according to the presentembodiment. FIG. 2 is a diagram for explaining a production process of aprinted board 40 of the battery pack 100 of the present embodiment. FIG.3 is a perspective view of the battery pack 100 of the presentembodiment. FIG. 4 is a cross-sectional view of FIG. 3 taken along A-A′.

The battery pack 100 includes a housing that is made up of a firstcasing 10 and a second casing 20; major components are housed in thehousing. For example, the major components that are housed in the firstcasing 10 and the second casing 20 include a battery cell assembly 30,which is made up of lithium-ion-battery unit cells that are connected inseries or parallel, or in both; a printed board 40, on which a circuitfor managing and controlling the battery cell assembly 30 is provided;and electrical wiring and the like, which are not shown.

On the printed board 40, chip-type LEDs 71 to 75 and a switch 76, whichmake up an indicator section 70, are placed and fixed by soldering orthe like. Moreover, on the printed board 40, besides the chip-type LEDs71 to 75 and the switch 76, a plurality of electrical components 80 areplaced and fixed by soldering or the like.

On the second casing 20, LED openings 21 to 25 are provided in such away as to correspond to the chip-type LEDs 71 to 75, allowing a user tocheck, from outside the housing, whether the chip-type LEDs 71 to 75 areon or off. Moreover, on the second casing 20, a movable piece 26 isprovided in such a way as to correspond to the switch 76. The switch 76is turned on by an external force that is applied through the movablepiece 26.

In a portion of the second casing 20 where the indicator section 70 isprovided, a transparent sealing seal 50, on which embossed portions 51to 56 are provided, is placed to seal the LED openings 21 to 25 and themovable piece 26.

According to the above-described configuration, for example, during aperiod of time in which a user is pushing the switch 76, the chip-typeLEDs 71 to 75 are turned on or off to notify a user of the charge levelof the battery cell assembly 30.

After a step of mounting the chip-type LEDs 71 to 75 and the electricalcomponents 80 on the printed board 40 by soldering, a step of applyingmoisture-proof resin 60 to the printed board 40 is carried out. In thismanner, the printed board 40 is given waterproof properties. As suchmoisture-resistant resin, for example, SE9187L manufactured by DowCorning Toray Co., Ltd. may be used.

FIG. 2 shows a step of applying the moisture-proof resin 60 to theprinted board 40. The printed board 40 on which the chip-type LEDs 71 to75, the switch 76 and the electrical components 80 have been fixed bysoldering is placed on an XY stage, which is not shown in the diagram.On the XY stage, a dispenser 90, which supplies the moisture-proof resin60, is provided. The printed board 40 is moved by the XY stage when themoisture-proof resin 60 is supplied from the dispenser 90. As a result,the chip-type LEDs 71 to 75, switch 76 and electrical components 80 onthe printed board 40 are integrally covered with the moisture-proofresin 60. Incidentally, some of the electrical components 80 are largerin height than the chip-type LEDs 71 to 75. The electrical components 80that are larger in height than the chip-type LEDs 71 to 75, too, arecovered with the moisture-proof resin 60 together with the chip-typeLEDs 71 to 75.

In the case of the battery pack 100 of the present embodiment, themoving speed of the XY stage and other factors are adjusted, so thatheight h₁ of the moisture-proof resin 60 between the chip-type LEDs 71to 75 from the board surface of the printed board 40 is set smaller thanheight h₂ of the moisture-proof resin 60 on the chip-type LEDs 71 to 75from the board surface of the printed board 40, as shown in FIG. 4. Whencompared with height h_(d) of the chip-type LEDs 71 to 75, h₁<h_(d)<h₂.

According to the battery pack 100 of the present invention, even if themoisture-proof resin 60 functions as a medium that conveys the lightemitted from the chip-type LEDs 71 to 75, there is almost no leakage oflight into the adjacent LEDs, and a LED that is not emitting light istherefore not mistaken as emitting light. As a result, it is possible tolet a user accurately know the state of charge of the battery pack.Moreover, in the case of the battery back 100 of the present invention,there is no need to put partition walls between the LEDs. Therefore, itis possible to reduce costs.

Incidentally, height h₁ of the moisture-proof resin 60 between thechip-type LEDs 71 to 75 is set smaller than height h₂ of themoisture-proof resin 60 on the chip-type LEDs 71 to 75. To realize thisconfiguration, the amount of moisture-proof resin 60 being supplied fromthe dispenser 90 is kept constant, and the moving speed of the XY stageis adjusted. Other methods, described below, may be used as well.

According to a first method, while the moving speed of the XY stage iskept constant, the amount of moisture-proof resin 60 being supplied fromthe dispenser 90 is changed according to the place where themoisture-proof resin 60 is supplied. As a result, height h₁ of themoisture-proof resin 60 between the chip-type LEDs 71 to 75 is setsmaller than height h₂ of the moisture-proof resin 60 on the chip-typeLEDs 71 to 75.

According to a second method, after the moisture-proof resin 60 isformed on the printed board 40 without any difference in height, acertain amount of the moisture-proof resin 60 is scrapped off betweenthe chip-type LEDs 71 to 75. As a result, height h₁ of themoisture-proof resin 60 between the chip-type LEDs 71 to 75 is setsmaller than height h₂ of the moisture-proof resin 60 on the chip-typeLEDs 71 to 75.

A comparison was made between the battery pack 100 of the presentembodiment shown in FIG. 4 and battery packs 100 of comparative examplesshown in FIGS. 5 to 7 in terms of the leakage of light into adjacentLEDs and water resistance. The results will be shown below.

In the battery pack 100 of a comparative example of FIG. 5, the heightof the moisture-proof resin 60 is set almost equal to that of thechip-type LEDs 71 to 75.

In the battery pack 100 of a comparative example of FIG. 6, the heightof the moisture-proof resin 60 is set higher than that of the chip-typeLEDs 71 to 75.

In the battery pack 100 of a comparative example of FIG. 7, the heightof the moisture-proof resin 60 is set lower than that of the chip-typeLEDs 71 to 75.

Table 1 shows the results of experiments on light leakage and waterresistance for the battery pack 100 of the present embodiment, which hasthe above-described configuration, and the battery packs 100 of thecomparative examples.

TABLE 1 Light leakage Water resistance Present invention Not observed ◯(FIG. 4) Comparative example Observed Δ (FIG. 5) Present inventionObserved ◯ (FIG. 6) Comparative example Not observed Δ (FIG. 7)In column “water resistance”, “◯” means that the water resistance isgood; “Δ” means that there is a possibility of water permeation on thesurface of the printed board 40 as a result of water adhering theretofor a long time.

As described above, in the battery pack 100 of the present invention,the height of the moisture-proof resin 60 between a plurality of thechip-type LEDs 71 to 75 from the board surface of the printed board 40is set lower than the height of the moisture-proof resin 60 on aplurality of the chip-type LEDs 71 to 75 from the board surface of theprinted board 40. According to the battery pack 100 of the presentinvention, even if the moisture-proof resin 60 functions as a mediumthat conveys the light emitted from the LEDs, there is almost no leakageof light into the adjacent LEDs, and a LED that is not emitting light istherefore not mistaken as emitting light. As a result, it is possible tolet a user accurately know the state of charge of the battery pack 100.

Moreover, in the battery pack 100 of the present invention, themoisture-proof resin 60 is provided on a plurality of the chip-type LEDs71 to 75 as well. Therefore, the battery pack 100 is excellent in waterresistance.

Moreover, in the battery pack 100 of the present invention, there is noneed to put partition walls between the LEDs . Therefore, it is possibleto reduce costs.

INDUSTRIAL APPLICABILITY

The present invention relates to a battery pack that includes aplurality of LEDs coated with moisture-resistant resin as an indicatorsection in order to let a user know a remaining amount of batterycapacity. In such a battery pack, the moisture-resistant resin functionsas a medium that conveys light emitted from the LEDs. As a result, auser might see the LED that is not emitting light as one that isemitting light. The problem is therefore that this configuration makesit difficult to let the user know exactly the state of charge of thebattery pack. In the battery pack of the present invention, the heightof the moisture-proof resin between a plurality of LEDs from the boardsurface is set lower than the height of the moisture-proof resin on theplurality of LEDs from the board surface. According to the battery packof the present invention, even if the moisture-resistant resin functionsas a medium that conveys the light emitted from the LEDs, there isalmost no leakage of light into the adjacent LEDs, and a LED that is notemitting light is therefore not mistaken as emitting light. As a result,it is possible to let a user accurately know the state of charge of thebattery pack. Therefore, the present invention is very high inindustrial applicability.

EXPLANATION OF REFERENCE SYMBOLS

-   10: First casing-   20: Second casing-   21: LED opening-   22: LED opening-   23: LED opening-   24: LED opening-   25: LED opening-   26: Movable piece-   30: Battery cell assembly-   40: Printed board-   50: Transparent sealing seal-   51: Embossed portion-   52: Embossed portion-   53: Embossed portion-   54: Embossed portion-   55: Embossed portion-   56: Embossed portion-   60: Moisture-proof resin-   70: Indicator section-   71: Chip-type LED-   72: Chip-type LED-   73: Chip-type LED-   74: Chip-type LED-   75: Chip-type LED-   76: Switch-   80: Electrical component-   90: Dispenser-   100: Battery pack

1. A battery pack comprising: a plurality of LEDs; a board on which theplurality of LEDs are placed; a casing where openings are provided insuch a way as to correspond to the plurality of LEDs; and moisture-proofresin that is provided in such a way as to cover the plurality of LEDson the board, wherein height of the moisture-proof resin between theplurality of LEDs from a surface of the board is lower than height ofthe moisture-proof resin on the plurality of LEDs from the surface ofthe board.
 2. The battery pack according to claim 1, wherein theplurality of LEDs are covered with the moisture-proof resin.
 3. Thebattery pack according to claim 1, wherein: a component that is higherthan the plurality of LEDs is placed on the board together with theplurality of LEDs; and the component is covered with the moisture-proofresin integrally with the plurality of LEDs.
 4. The battery packaccording to claim 2, wherein: a component that is higher than theplurality of LEDs is placed on the board together with the plurality ofLEDs; and the component is covered with the moisture-proof resinintegrally with the plurality of LEDs.